Gereedschappen die in deze demontage worden gebruikt

Inleiding

Here's a Sony wireless stereo earphone system consisting of an infrared transmitter and receiver pair, dating from around 1993. At that time, there was no such thing as an iPod and so the smallest personal audio players were cassette tape Walkmans or compact disc Discmans. With this wireless earphone kit, you could listen to your stereo, free to wander around the room without one of those 10 foot headphone cords or without a relatively bulky audio player attached to your belt.

Of course nowadays, you can have thousands of songs in an even smaller device attached to your shirt sleeve, so this kind of audio accessory is not so interesting any more for most consumers. However, this same basic technology is still in use in many places - for example some auditoriums will have large IR arrays providing wireless audio to the hearing impaired in the audience.

Voeg opmerking toe

Here's the transmitter mast with the front lens/cover of the housing removed. Inside we see an array of infrared LEDs.

Next remove the 4 Phillips screws. Two of the screws fasten the metal hinge to the back half of the housing (one is partially obscured by the hinge in the first photo).

The other two screws fasten the LED circuit board to the back half of the housing.

The third photo shows a closer view of some of the infrared LEDs. There are 12 LEDs in all. They emit no visible light - but did you know? the IR beam can be seen by most camcorders and digital cameras.

The LEDs transmit the audio signal using FM modulation of the IR beam. The carrier frequencies used are 2.3MHz for the left channel, and 2.8MHz for the right. The specification for maximum range is 9 meters.

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Here are front and rear views of the IFR-33 infrared receiver. It's bigger than an iPod shuffle and carries no songs! ...or maybe it carries an infinite number of songs, connected to your stereo or other audio system, depending on how you look at it...

On the back, you'll find a swiveling clip and the battery compartment cover.

In use, the receiver can be clipped to your belt or shirt. The kit also comes with a lanyard (not shown) that let's you wear the receiver around your neck. Standard stereo earphones can be plugged into a jack at the bottom of the receiver.